That sparked an event known as the Paleocene-Eocene Thermal Maximum (PETM) when temperatures rose by five to eight degrees Celsius (9 to 14 degrees Fahrenheit).

It killed off both land and sea animals — and took more than 150,000 years for the planet to return to normal. This has been used as a benchmark for modern climate change in the past. But the latest finding shows we are on track to meet it much sooner than feared.

The pace of today’s warming far outstrips any climate event that has happened since the extinction of the dinosaurs.